Computational Study of Field Scale BTEX Transport and Biodegradation in the Subsurface

In this work we simulate numerically the transport and biodegradation of an organic contaminant (BTEX) in the subsurface. A “real world” contaminated site is considered and realistic laboratory-derived or field-measured input parameters are used. The biodegradation of the dissolved contaminant plume is modelled by Monod type kinetics. For the computations we use an approximation scheme which is based on a higher order finite element method and the two step backward differentiation formula and was proposed and carefully analyzed by the author in a recent work [3]. It was successfully applied to test (benchmark) problems reported in the literature (cf. [10, 13]) as well as complex scenarios with an additional numerical computation of the flow field by solving the parabolic-elliptic degenerate Richards equation; cf. [3]. The higher order approximation scheme has shown to reduce significantly the amount of inherent numerical diffusion compared to lower order ones. Thereby an artificial transverse mixing of the species leading to a strong overestimation of the biodegradation process and wrong prediction is avoided.